Field studentsMapper in site.longkui.app.service.StudentsService required a bean of type ‘site.longkui.app.mapper.StudentsMapper’ that could not be found.

某日新創建spring boot項目后啟動項目報錯：

Description:

Field studentsMapper in site.longkui.app.service.StudentsService required a bean of type 'site.longkui.app.mapper.StudentsMapper' that could not be found.

The injection point has the following annotations:
	- @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean of type 'site.longkui.app.mapper.StudentsMapper' in your configuration.

這個錯誤是因為我們沒有加上MapperScan注解。

我們找到啟動類，在前面加上@MapperScan注解，并加入需要掃描是包路徑。比如下面這樣：

@SpringBootApplication
@MapperScan("site.longkui.**.mapper")
public class AppApplication {

    public static void main(String[] args) {
        SpringApplication.run(AppApplication.class, args);
    }

}

其中，**表示模糊匹配，方便后期項目進行擴展。然后重新啟動項目就正常了。